lake in central South Island, New Zealand, occupying 37 square miles (96 square km) of a valley that has been dammed by a moraine (glacial debris). The lake is about 15 miles (24 km) long and 3.5 miles (6 km) wide and drains a 550-square-mile (1,425-square-kilometre) basin. The lake's major affluents, east of the Southern Alps, are the Godley and Macaulay rivers. Near the resort town of Lake Tekapo at its southern tip, the lake empties through the Tekapo River.

Lake Tekapo lies at an elevation of 2,346 feet (715 m) and is about 620 feet (190 m) deep, but its level may vary as much as 25 feet (8 m), as water is drawn off by an outlet dam for hydroelectric stations downstream. The name Tekapo is derived from two Maori words, taka, or teka (“sleeping mat”), and po (“night”).